itimers: remove the per-cpu-ish-ness

Either we bounce once cacheline per cpu per tick, yielding n^2 bounces
or we just bounce a single..

Also, using per-cpu allocations for the thread-groups complicates the
per-cpu allocator in that its currently aimed to be a fixed sized
allocator and the only possible extention to that would be vmap based,
which is seriously constrained on 32 bit archs.

So making the per-cpu memory requirement depend on the number of
processes is an issue.

Lastly, it didn't deal with cpu-hotplug, although admittedly that might
be fixable.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index 2f3c2d4ef73b..ea0ea1a4c36f 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -48,6 +48,12 @@ extern struct fs_struct init_fs;
         .posix_timers    = LIST_HEAD_INIT(sig.posix_timers),            \
         .cpu_timers     = INIT_CPU_TIMERS(sig.cpu_timers),              \
         .rlim           = INIT_RLIMITS,                                 \
+        .cputime        = { .totals = {                                 \
+                .utime = cputime_zero,                                  \
+                .stime = cputime_zero,                                  \
+                .sum_exec_runtime = 0,                                  \
+                .lock = __SPIN_LOCK_UNLOCKED(sig.cputime.totals.lock),  \
+        }, },                                                           \
 }
 
 extern struct nsproxy init_nsproxy;